I received this reply from tech support...
The sync button was removed because it generated complex issues.
To make changes on your Control maps / sequences on your computer, simply make the changes you want in the Midi Control Center, select "Working Project" and hit the "Store" button. (Storing on individual projects is known to have bugs right now so remember to use the Working project and not individual projects)
Then on the Beatstep pro, save the project on the slot that you prefer.
The manual is in the process of being changed !